After years of conserving water, the city's usage has surged this year.

A hot summer and easing water restrictions have coincided with a big jump in water use. In the week to January 10, Melburnians used an average of 238 litres per person - 50 per cent more than the former daily usage target of 155 litres a day.

It was the highest weekly per capita water use since the week ending February 15, 2009, when 241 litres a day were used.

In the week ending Thursday, average daily water use per person was 225 litres, 45 per cent above the former 155 target.

The Baillieu government eased water restrictions on the first day of summer, allowing residents to use sprinklers on any day of the week between 6pm and 10am. The permanent water use rules also allow people to wash paved areas ''for health and safety reasons or to remove stains once a season, using either a hose fitted with a trigger nozzle or a high pressure cleaning device''.

The changes follow an easing of restrictions in late 2011 to allow watering of gardens and lawns using a hose fitted with a trigger nozzle at any time on any day and allowing car washing at home with a hose using a trigger nozzle or a high pressure hose.

Water Minister Peter Walsh denied there had been a cultural shift in Melbourne back to heavy water use. ''Melbourne has had some very hot days recently, we haven't had a lot of rain, and it's summer. It is not uncommon for water use to peak during such hot and dry conditions,'' he said.

''After restrictions eased to permanent water saving rules last November, water use generally has continued to trend at similar levels, which indicates that the lessons Melbourne customers learnt during the drought about using water wisely have stayed with them.''

Opposition water spokesman John Lenders said the government was managing Melbourne's water recklessly.

''I think the government is simply reckless and it is driven by ideology rather than any science. Melbourne continues to grow at 80,000 people a year. Climate change is real no matter what some people try to spin.''

In the past week, Melbourne's water storages fell by 10.8 billion litres - double the average summer weekly storage drop. Stream flows into the city's reservoirs were less than half the 30-year average for the period.

Recent dry conditions follow a good year for Melbourne's water storages, which gained over 265 billion litres in 2012 and are now 79.4 per cent full.

Mr Walsh said it was too early to say if the government would place its first order from the water desalination plant in coming months.